Electric motor and fan wheel combination, and method for producing it

ABSTRACT

An electric motor having a housing, having an armature, having an armature shaft supported in two slide bearings, where one of the slide bearings axially displaceably receives the armature shaft and the other slide bearing limits an axial displaceability of the armature shaft by the disposition of a stop disk between a slide bearing bush of the slide bearing and the armature, by the disposition of an axial stop, in the form of a stop ring pressed over one end of the armature shaft. The armature shaft end protrudes out of the housing and is intended for carrying and driving a fan wheel that has a hub which is located adjacent the particular a slide bearing that receives only radial forces. The armature shaft end that carries the fan wheel is associated with the particular slide bearing that is designed as a bidirectionally acting axial bearing, and the hub of the fan wheel is brought so close to a face-end running face of the slide bearing bush that this hub on its face end forms an axial stop of the axial bearing. As a result, a special stop ring is unnecessary.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is based on an electric motor and fan wheel combination asdefined hereinafter.

2. Description of Related Prior Art

U.S. Pat. No. 3,264,506 discloses an electric motor and fan wheelcombination having a housing, having an armature and a collector in thehousing, two slide bearings in the housing, an armature shaft supportedby means of the slide bearings and carrying the armature and thecollector. The armature has an armature shaft end protruding out of thehousing, and a fan wheel that has a hub which is secured to the armatureshaft end. Both slide bearings have slide bearing bushes, disposed insuch a way that they can execute tilting motions, with face-end bearingfaces, so that the slide bearing bushes together with the armature shaftform two radial bearings, and that face-end bearing faces of the twoslide bearing bushes oriented toward the armature and the collector,together with annular disks built in between them and the armature andthe collector and surrounding the armature shaft, additionally form twoaxial bearings. These axial bearings limit the displaceability of thearmature shaft in the axial direction. To enable setting the axial playto a magnitude of substantially 0.125 mm, for example, the housing ofthe electric motor comprises two substantially cup-shaped housing parts,one of which can be inserted in telescoping fashion into the other toreduce the originally excessive longitudinal armature play to thedesired value, which is associated with less noise in operation of theelectric motor. Once the axial play has been set to the intended value,weld seams are made on the two housing parts, so that the mutualorientation of the housing parts and thus the set axial play arepreserved. In this state, the hub of the fan wheel has an axial spacingfrom an adjacent bearing bush. The annular disks are made from sheetsteel, for instance, and are embodied on their circumference in themanner of the rim of a plate, so that in addition to furnishing axialbearing slide faces, they also act as spinner rings for oil, with whichthe porous slide bearing shells are saturated.

U.S. Pat. No. 3,624,434 discloses an electric motor that is intended forinstance for combination with the fan wheel of the aforementioned U.S.Pat. No. 3,264,506. This electric motor has a housing, an armature, acollector, and two slide bearings in the housing. An armature shaft issupported by means of the slide bearings and carries both the armatureand the collector and has an armature shaft end protruding out of thehousing, on which end a hub of the fan wheel is secured. Both slidebearings have slide bearing bushes with face-end bearing faces, theslide bearings receiving the armature shaft, and both face-end bearingfaces of one of the slide bearing bushes, together with an annular diskdisposed between the collector and this slide bearing bush about thearmature shaft, and with an axial bearing, press-fitted on the far sideof the annular disk on a free end of the armature shaft that is insertedthrough the slide bearing, forms a bidirectional axial bearing for thearmature shaft. As a result, the slide bearing, formed of the annulardisk, the axial stop ring and the sliding bush located between them,forms what in German is called a fixed bearing, while conversely theother slide bearing, which is adjoined by the armature shaft endintended for the fan wheel, is known in German as a loose bearing. Whatthis means is that this loose bearing generates only radial bearingforces and does not present any resistance to displacement of thearmature shaft, or in other words loosely receives the armature shaft inthe is axial direction. The annular disk, as a component of the axialbearing, is made from sheet metal and has a rim similar to that of aplate, so that the annular disk, in addition to furnish an axial bearingface, also acts as an oil spinner ring to prevent oil from migrating outof the porous slide bearing bush to the collector.

SUMMARY OF THE INVENTION

The electric motor and fan wheel combination according to the inventionis economical, because a hub, which is required anyway, of the fanwheel, makes the task of the axial stop ring of the prior art forforming an axial bearing unnecessary. This accordingly saves oninstallation space in the housing of the electrical motor in the priorart that is intended for the axial stop ring.

By means of the characteristics recited herein advantageous embodimentsof the electric motor and fan wheel combination defined are possible.

The definitive characteristics set forth herein have an advantage of anelastic and thus noise-reducing limitation of the displaceability of thearmature shaft relative to the housing of the electric motor.Accordingly, the hub of the fan wheel is prevented from striking theslide bearing bush hard and thus the projection of irritating clackingnoises through the housing of the electric motor of the fan wheel isaverted.

Other definitive characteristics disclose an exemplary embodiment thatcan be produced economically.

Yet other definitive characteristics set forth can be employedalternatively and offer the advantage of easier mounting of the hub ofthe fan wheel on the armature shaft end, because a press fit can beembodied less rigidly. For the exemplary embodiments set forth, asliding fit suffices for disposing the respective hub on the armatureshaft end.

The method defined by the characteristics the advantage that to set theaxial play, there is no need to introduce a feeler gauge between theslide bearing bush and the hub of the fan wheel. As a result, beginningat the hub, a carrier body that carries a number of fan blades can beembodied in shell-like fashion, surrounding the electric motor over aportion of its length.

The method having the definitive characteristics set forth herein areemployed to produce the electric motor and fan wheel combination.

BRIEF DESCRIPTION OF THE DRAWINGS

Four exemplary embodiments of the electric motor and fan wheelcombination of the invention are shown in the drawings and described infurther detail below.

FIG. 1 shows a first exemplary embodiment of the electric motor and fanwheel combination of the invention in longitudinal section;

FIG. 2 shows a refinement of the exemplary embodiment of FIG. 1;

FIG. 3 shows a third exemplary embodiment; and

FIG. 4 shows a fourth exemplary embodiment of an electric motor and fanwheel combination.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first exemplary embodiment of an electric motor and fan wheelcombination 2 in FIG. 1 comprises an electric motor 3 and a fan wheel 4that is driven by the electric motor.

The electric motor 3 has a housing 5, which comprises a tubularshort-circuit body, 6 and substantially cup-shaped housing parts 7 and 8attached to the short-circuit body; and at least one permanent magnet 9disposed in the short-circuit body 6. An armature 10 includes anassociated collector 11; at least one carbon brush 12 and carbon brushguide means 13; an armature shaft 14; and two slide bearings 15, 16 thatreceive the armature shaft 14. In the exemplary embodiment, the slidebearings 16 have slide bearing bushes 17, which have face-end bearingfaces 18 that preferably extend in circular-annular fashion. On theoutside, the slide bearing bushes, in a manner known per se, havedomelike zones 19 for the sake of tiltable reception in the housingparts 7 and 8. To that end, the housing parts 7 and 8 have funnel-likerecesses, against which the slide bearing bushes 17 are pressed byspring tongues 20 that originate at clamping brackets 21.

An element 22 that in the manner of an annular disk surrounds thearmature shaft 14 and is inserted between the collector 11 and the slidebearing 16, or its slide bearing bush 17, and in the region of its outerrim this element is shaped in platelike fashion, so that the element canact as an oil spinner ring for oil that may creep out of the slidebearing bush 17 along the armature shaft and that should be kept awayfrom the collector 11. A structurally identical element 22 is alsoinserted between the armature 10 and the slide bearing bush 17 of theslide bearing 15. Here, the element 22 serves as an annular stop diskthat cooperates with a face-end bearing face 18 of the slide bearingbush 17. For example, this element 22 is produced from a rubberlikeelastic material, such as a thermoplastic elastomer. As a result, theelement 22 prevents the creation of metal impact noises on the occasionof unavoidable relative motions of the armature 10 in the direction ofthe slide bearing bush 17 retained in the housing part 7.

The armature shaft 14 has an armature shaft end 23, which protrudesthrough the slide bearing bush 17 out of the housing part 7, forsupporting and driving the fan wheel 4. To that end, the fan wheel 4 hasa hub 24, which encloses the armature shaft end 23 and which in thefirst exemplary embodiment is press-fitted onto the armature shaft end23. As a result, the hub 24 is adequately secured both axially andcircumferentially relative to the armature shaft end 23. Toward theadjacent bearing face 18 of the slide bearing bush 17, the hub 24 has anaxial stop face 25. The element 22 acting here as a stop disk is bracedin an arbitrary way, for instance as in the prior art, indirectly in theaxial direction relative to the armature 18. In FIG. 1, the element 22is shown resting on a bearing face 18 of the slide bearing bush 17located in the housing part 7, while conversely an axial spacing A isshown between the other bearing face 18, which belongs to this slidebearing bush 17, and the axial stop face 25 of the hub 24. This axialspacing A is adjustable by axial orientation of the hub 24 relative tothe element 22 supported indirectly on the armature 10. This axial playA is shown exaggeratedly large in FIG. 1 and in practice is set forinstance to 0.1 mm.

Between the slide bearing bush 17 and housing part 8 and the element 22accommodated there, a spacing B is provided. This spacing B isintentionally greater than the above-described spacing A. As a result,the armature shaft is longitudinally displaceable without hindrance, asintended, inside the slide bearing bush 17 carried by the housing part8, while conversely the displaceability of the armature shaft 14relative to the slide bearing bush 17 retained in the housing part 7 islimited to the amount of the axial spacing A. As a result, the slidebearing 15 carried by the housing part 7 is both a radial slide bearingand a bidirectional axial bearing and thus is known in German as aso-called fixed bearing. In contrast to this, the other slide bearing16, as already indicated by the intrinsically unlimited displaceabilityof the armature shaft 14, is a so-called loose bearing.

Adjoining the hub 24 of the fan wheel 4 is a wheel disk 26, which in thefirst exemplary embodiment is embodied essentially in keylike form,which has fan blades 27 on its circumference. These blades are shown insimplified fashion and are fixed relative to one another, axially spacedapart from the wheel disk 26, by means of a ring 28. The hub 24, wheeldisk 26, fan blades 27 and ring 28 are in this example injection moldedas an integral component of a thermoplastic material. However, anengineer is free to produce the fan wheel 4 at least in part of a metalmaterial. For instance, the fan wheel 4 can also be secured on thearmature shaft end in accordance with U.S. Pat. No. 3,264,506.

If, as in the example shown in FIG. 1, the keylike wheel disk 26 makesaccess to the axial play A between the slide bearing bush 17 and theaxial stop face 25 of the hub 24 difficult or impossible, then the axialplay A is set in accordance with the method described below:

A face end 29, located in the housing part 8, of the armature shaft 14is braced in a manner not shown once the electric motor 3 has beenassembled. Then, counter to the bracing, not shown, the hub 24 isbrought into alignment with the armature shaft end 23 and ispress-fitted along this end onto the armature shaft 14, leaving an axialspacing between the axial stop face 25 and the associated slide bearingbush 17; this axial spacing is with certainty greater than the axialspacing A to be set. Then, the housing 5 of the electric motor 3 is forinstance displaced relative to the armature shaft 14, and the magnitudeof the displacement distance is measured, for instance taking intoaccount an incident elastic compression of the element 22 that isassociated with the slide bearing 15. From the thus-ascertaineddisplacement measurement, a value on the order of the intended axialplay A is subtracted, and the result obtained indicates a displacementmeasure for a further displacement of the hub 24 relative to thearmature 10 by means of a press. This method can be performed forinstance by hand or by machine. In the latter case, a controller for thepress is needed, which is given its specifications from an automaticdisplacement travel measuring instrument.

The second exemplary embodiment of an electric motor and fan wheelcombination 2 a of FIG. 2 differs from the exemplary embodiment of FIG.1 in that a buffer ring 30 is inserted between the hub 24 of the fanwheel 4 and the adjacent slide bearing bush 17 of the slide bearing 15.This buffer ring 30 is for instance, like element 22, produced from arubberlike elastic material, such as thermoplastic elastomer, and as itsname says, it acts as a buffer element on the one hand, but on the otheralso as a ringlike stop disk, so that as in the example of FIG. 1 theslide bearing 15 also acts as an axial bearing. Once again, an axialplay A of this slide bearing 15 is shown exaggeratedly large between theslide bearing bush 17 and the buffer ring 30. The axial play A is shownin the drawing at this point because, as a result of the relativedisplacement of the housing 5 mentioned in the method described relativeto the armature shaft 14 and thus to the armature 10, whenever thebuffer ring 30 surrounds the armature shaft end 23 A with radialtension, has a tendency to remain at the hub 24. It can be seen that bythe disposition of the buffer ring 30, a direct mechanical contactbetween the slide bearing bush 17, which is normally made of metal, andthe hub 24 of the fan wheel 4, which is made of relatively hard plasticor metal, is avoided. The prevention of a hard mechanical contact bymeans of the buffer ring 30 is accordingly a noise-abatement provision.

The third exemplary embodiment of an electric motor and fan wheelcombination 2 b in FIG. 3 differs from the first exemplary embodiment inFIG. 1 in that a hub 24 b of a fan wheel 4 b is embodied to receive atleast one clamping screw 31. For example, this clamping screw 31 has ahexagonal socket 32 known per se and is headless and therefore takes theform of a so-called threaded pin. A clamping screw 31 of this kind canbe disposed as a fastening means in addition to the above-describedpress fit, of the hub 24 on the armature shaft end 23 of theabove-described exemplary embodiment. On the other hand, thanks to thedisposition of the at least one clamping screw 31, a less-rigid pressfit or a transitional fit, even extending to a sliding fit, can also beprovided. This makes it easier to adjust the hub 24 b relative to thearmature 10.

The fourth exemplary embodiment of an electric motor and fan wheelcombination 2 c of FIG. 4 differs from the third exemplary embodiment ofFIG. 3 in that a hub 24 c of a fan wheel 4 c has a groove 33, inclinedtoward the armature shaft end 23, into which a wedge 34 can be driven.As a result, a rigid press fit in the first exemplary embodiment can bedispensed with. For instance, a sliding fit can be provided for thealignment of the hub 24 c on the armature shaft end 23, and adisplacement resistance that is advantageous for setting the axial playA can be generated by means of the wedge 34, by displacement of thewedge in the groove 33.

From the description of the differences in terms of how the various hubs24, 24 b and 24 c are secured to the respective armature shaft end 23,it can be seen that the idea of creating an axial bearing with anadjustable axial play A, with the aid of an axial stop face located on ahub of a fan wheel, is independent of the way in which the applicablehub is in the final analysis secured in an operationally reliable way tothe associated armature shaft end. For example, if such a hub is ofsteel, it could be secured by the provision of a weld seam.

The above-described use of a hub of a fan wheel as a component of anaxial bearing, which has a slide bearing bush 17 with end-face bearingfaces 18, is not tied to the disposition shown in FIG. 1 of a collector11. Instead, an axial bearing of the type described can also be used ina differently designed electric motor of an electric motor and fan wheelcombination.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodiments aretherefore possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

We claim:
 1. An electric motor and fan wheel combination, comprising ahousing, an armature in the housing, first and second slide bearings(15, 16) in the housing, an armature shaft (14) supported by the firstand second slide bearings and carrying the armature (10), the armaturehas an armature shaft end (23), and a fan wheel (4), said fan wheel hasa hub (24) that is secured to the armature shaft end for rotation withthe armature shaft end, and the first and second slide bearings havefirst and second slide bearing bushes (17, 17), each of the first andsecond slide bearing brushes include inner and outer bearing end faces(18, 18), the first and second slide bearing bushes (17, 17) receive thearmature shaft, and the inner end face of the first slide bearing bush(17), together with an annular disk-like element (22) disposed betweenthe armature and the inner bearing end face of the first slide bearingbush surrounds the armature shaft, and an axial stop (25) orientedtoward the outer bearing end face of the first slide bearing bush andsecured on the armature shaft, form the first slide bearing acting intwo directions, and the hub (24, 24 b, 24 c) of the fan wheel (4, 4 b, 4c) forms the axial stop (25) of the first slide bearing (15).
 2. Theelectric motor and fan wheel combination of claim 1, in which a bufferring (30) of rubberlike elastic material and surrounding the armatureshaft end (23) is built-in between the hub (24) of the fan wheel (4) andthe outer end of the bearing face end (18) of the first slide bearingbush (17) of the first slide bearing (15).
 3. The electric motor and fanwheel combination of claim 1, in which the hub (24) of the fan wheel (4)is press-fitted onto the armature shaft end (23, 23 a).
 4. The electricmotor and fan wheel combination of claim 2, in which the hub (24) of thefan wheel (4) is press-fitted onto the armature shaft end (23, 23 a). 5.The electric motor and fan wheel combination of claim 1, in which thehub (24 b) of the fan wheel (4 b) is fixed on the armature shaft end(23) by means of at least one clamping screw (31).
 6. The electric motorand fan wheel combination of claim 2, in which the hub (24 b) of the fanwheel (4 b) is fixed on the armature shaft end (23) by means of at leastone clamping screw (31).
 7. The electric motor and fan wheel combinationof claim 1, in which the hub (24 c) of the fan wheel (4 c) is fixed onthe armature shaft end (23) by means of a wedge (34).
 8. The electricmotor and fan wheel combination of claim 2, in which the hub (24 c) ofthe fan wheel (4 c) is fixed on the armature shaft end (23) by means ofa wedge (34).
 9. An electric motor and fan wheel combination as setforth in claim 1, which comprises a second disk-like element between theinner end of the second bush and the armature.
 10. A method forproducing an electric motor and fan wheel combination, having a housing,an armature in the housing, two slide bearings in the housing, anarmature shaft supported by means of the slide bearings and carrying thearmature, the armature shaft has an armature shaft end, and a fan wheel,which has a hub that is secured to the armature shaft end, and bothslide bearings have slide bearing bushes with bearing faces on the faceends, the slide bearing bushes receiving the armature shaft, and bothface-end bearing faces of one of the slide bearing bushes, together withan annular disk-like element disposed between the armature and thisslide bearing bush around the armature shaft with an axial stop,oriented toward the opposite face-end bearing face of this slide bearingbush and secured on the armature shaft, form an axial bearing acting intwo directions, and the hub of thee fan wheel, with an end orientedcounter to the first bearing face of the slide bearing bush, forms theaxial stop, the method comprising assembling the electric motor armatureshaft, and bearings, after the assembly, the hub (24, b, c) of the fanwheel (4, 4 b, 4 c) is thrust onto an armature shaft end (23, 23 a),leaving a spacing from an adjacent bearing face (18) of the adjacentslide bearing bush (17); displacing the armature shaft (14) at leastonce; and measuring the displacement distance to provide a value on theorder of magnitude (A) of an intended axial play (A), subtracting thevalue from the measured value of the displacement distance, and thatbased on a value calculated in this way, a displacement device isassembled for displacing the hub (24, b, c) on the armature shaft end(23, 23 a) in the direction of the armature (10) by a displacementdistance associated with the calculated value.
 11. The method of claim10, in which a controllable press is used as the displacement device,which, on a face end engaging the hub (24, b, c), presses in thedirection of the armature (10), while the armature shaft (14) is bracedon a face end.